A goal of some developers of sound producing apparatus is to provide more acoustic power in a smaller product package. Obtaining a smaller product package can be challenging, particularly where a waveguide is used to enhance the low frequency output of the apparatus. Typically, an electro-acoustic transducer emits acoustic waves into the waveguide. The air volume located adjacent to the transducer adds to the size of the apparatus. If the air volume adjacent to the transducer could be minimized, the size of the apparatus could be reduced.
Providing more acoustic power in a smaller product package often involves using a more powerful electromagnetic motor in the electro-acoustic transducer. The use of a more powerful motor increases the amount of stray magnetic flux generated by the motor that extends beyond the product package. If the sound producing apparatus is placed too close to another electronic device (e.g. a video monitor), the stray magnetic flux could damage the electronic device. Containing the magnetic flux is important in order to not damage other electronic devices.